Terminal device, communication method, and communication system

ABSTRACT

A method that carries out uplink multiple access while reducing complexity in processing accompanying exchange of control information. A terminal device that performs uplink multiple access communication includes a reception unit that receives a frame including uplink multiple access connection information, a first autonomous decentralized control unit that instructs securing time of a wireless resource, and a second autonomous decentralized control unit that instructs securing time of a wireless resource after reception of a frame including the uplink multiple access connection information. The terminal device is instructed securing time of the wireless resource by the first autonomous decentralized control unit in a case that a frame including the uplink multiple access connection information is not received. Securing time of the wireless resource is instructed by the second autonomous decentralized control unit in a case that a frame including the uplink multiple access connection information is received.

TECHNICAL FIELD

The present invention relates to a terminal device, a communicationmethod, and a communication system.

BACKGROUND ART

The IEEE (The Institute of Electrical and Electronics Engineers Inc.)has set forth IEEE 802.11ac, which realizes even higher speeds than IEEE802.11 that is a wireless LAN (Local Area Network) standard. The IEEEcurrently has started work on standardization of IEEE 802.11ax as asuccessor standard for IEEE 802.11ac. Improved throughput per user in anenvironment where wireless LAN devices are overcrowded is being studiedin standardization of IEEE 802.11ax as well, to handle the rapidincrease of wireless LAN devices.

A wireless LAN system is a system where each wireless LAN device securesits own resources in an autonomous decentralized manner (autonomousdecentralized system). An autonomous decentralized system is a system inwhich temporal synchronization among wireless LAN devices, and exchangeof complicated control information, are not required. Accordingly, awireless network can be configured using wireless LAN devices that havea relatively simple configuration. Autonomous decentralized systems arewell-suited for unlicensed band, due to the ease of configuring wirelessnetworks.

Usage situations of wireless LAN systems have become markedlydiversified due to the rapid spread thereof in recent years. Forexample, situations such as a wireless carrier using a wireless LANsystem for offloading wireless mobile communication traffic, providingpublic wireless LANs primarily targeting foreign tourists, and so forth,have already been realized, with wireless LAN base stations (AP: AccessPoint) being installed in train stations, large-scale commercialfacilities, and so forth. Thus, wireless LANs have been activelyinstalled in locations where people congregate, with Internet servicesbeing actively provided.

The standardization of IEEE 802.11ax aims to improve throughput inenvironments where wireless LAN devices are overcrowded, viewed againstthe background of diversity in usage situations of wireless LAN, andtechnology for introduction thereof is being studied.

One technology being studied for standardization of IEEE 802.11ax isuplink multiple access technology. Uplink multiple access technology istechnology where multiple LAN device perform transmissioncollaboratively, temporal synchronization among wireless LAN devices andexchange of control information being required of the wireless LANdevices. Accordingly, detailed discussion is being held instandardization of IEEE 802.11ax, with regard to temporalsynchronization of wireless LAN devices and procedures for exchange ofcontrol information.

NPL 1 proposes procedures for uplink MU-MIMO. According to NPL 1, awireless LAN base station transmits a frame that triggers initiation ofuplink MU-MIMO (trigger frame). An arrangement is used where a wirelessLAN device that has received the trigger frame initiates transfer ofdata at a predetermined point in time, if participation in the uplinkMU-MIMO has been instructed by the wireless LAN base station, therebyeasily enabling temporal synchronization among wireless LAN devices.

CITATION LIST Non Patent Literature

-   NPL 1: IEEE 802.11-15/0331r0 Uplink Multi-User MIMO Protocol Design

SUMMARY OF INVENTION Technical Problem

However, in a case of performing uplink MU-MIMO using the proceduresdescribed in NPL 1, the wireless LAN base station needs to comprehendinformation regarding data traffic of each wireless LAN device. Thismeans that there is a need to notify information regarding data trafficof each wireless LAN device to the wireless LAN base station as controlinformation, which complicates the wireless network.

The present invention has been made in light of the above, and it is anobject thereof to disclose a method of realizing uplink multiple accesswhile reducing complexity of wireless networks due to exchange ofcontrol information.

Solution to Problem

The terminal device, communication method, and communication system,according to the present invention, for solving the above-describedproblem, are as follows.

(1) That is to say, the terminal device according to the presentinvention is a terminal device that performs uplink multiple accesscommunication, including a reception unit that receives a frameincluding uplink multiple access connection information, a firstautonomous decentralized control unit that instructs securing time of awireless resource, and a second autonomous decentralized control unitthat instructs securing time of a wireless resource after reception of aframe including the uplink multiple access connection information. Theterminal device is instructed securing time of the wireless resource bythe first autonomous decentralized control unit in a case that a frameincluding the uplink multiple access connection information is notreceived. Securing time of the wireless resource is instructed by thesecond autonomous decentralized control unit in a case that a frameincluding the uplink multiple access connection information is received.

(2) The terminal device according to the present invention is theterminal device according to the above (1), wherein the secondautonomous decentralized control unit generates a CW that is differentfrom a CW that the first autonomous decentralized control unitgenerates.

(3) The terminal device according to the present invention is theterminal device according to the above (1), wherein the secondautonomous decentralized control unit references information instructingtransmission permissible determination within a frame including theuplink multiple access connection information. The second autonomousdecentralized control unit further determines participation in uplinkmultiple access connection based on the information instructingtransmission permissible determination.

(4) The terminal device according to the present invention is a terminaldevice that performs uplink multiple access communication, including atransmission unit that transmits a frame including uplink multipleaccess connection information, and a transmission power control unitthat performs transmission power control in accordance with a type oftransmission frame. The transmission unit differs in transmission powerat a time of transmitting a frame including the uplink multiple accessconnection information and transmission power at a time of uplinkmultiple access transmission.

(5) The terminal device according to the present invention is theterminal device according to the above (4), wherein prior totransmission of a frame including the uplink multiple access connectioninformation, the terminal device transmits a control signal using atransmission power than is different from the transmission power usedfor a frame including the uplink multiple access connection information.

(6) Also, the communication method of a terminal device according to thepresent invention is a communication method including at least a step ofreceiving a frame including uplink multiple access connectioninformation, a step of performing first autonomous decentralized controlwhere securing time of a wireless resource is instructed, a step ofperforming second autonomous decentralized control where securing timeof a wireless resource is instructed after reception of a frameincluding the uplink multiple access connection information, a step ofinstructing securing time of a wireless resource by the first autonomousdecentralized control in a case that a frame including the uplinkmultiple access connection information is not received, and a step ofinstructing securing time of a wireless resource by the secondautonomous decentralized control in a case that a frame including theuplink multiple access connection information is received.

(7) Also, the communication method of a terminal device according to thepresent invention is a communication method including at least a step ofreceiving a frame including uplink multiple access connectioninformation, and a step of performing first autonomous decentralizedcontrol in which securing time of a wireless resource is instructed.

(8) A communication system according to the present invention is acommunication system including a first terminal device and a secondterminal device. The first terminal device includes a reception unitthat receives a frame including uplink multiple access connectioninformation, a first autonomous decentralized control unit thatinstructs securing time of a wireless resource, and a second autonomousdecentralized control unit that instructs securing time of a wirelessresource after reception of a frame including the uplink multiple accessconnection information. The first terminal device is instructed securingtime of the wireless resource by the first autonomous decentralizedcontrol unit in a case that a frame including the uplink multiple accessconnection information is not received. Securing time of the wirelessresource is instructed by the second autonomous decentralized controlunit in a case that a frame including the uplink multiple accessconnection information is received. The second terminal device includesa transmission unit that transmits a frame including the uplink multipleaccess connection information, and a transmission power control unitthat performs transmission power control in accordance with a type oftransmission frame. The transmission unit differs in transmission powerat a time of transmitting a frame including the uplink multiple accessconnection information and transmission power at a time of uplinkmultiple access transmission.

Advantageous Effects of Invention

According to the present invention, terminal devices and a base stationcan form a suitable wireless network.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of the configuration of awireless communication system according to the present invention.

FIG. 2 is a diagram illustrating an example of the device configurationof a base station device according to the present invention.

FIG. 3 is a diagram illustrating an example of the configuration of anautonomous decentralized control unit according to the presentinvention.

FIG. 4 is a sequence chart illustrating an example of procedures forUL-MU transmission according to the present invention.

FIG. 5 is a diagram illustrating an example of the configuration of anMU initiation frame according to the present invention.

FIG. 6 is a sequence chart illustrating an example of procedures forUL-MU transmission according to the present invention.

FIG. 7 is a diagram illustrating an example of the configuration of thewireless communication system according to the present invention.

FIG. 8 is a diagram illustrating an example of GID configurationaccording to the present invention.

DESCRIPTION OF EMBODIMENTS

A communication system according to the present embodiment includes awireless transmission device (access point, base station device: Accesspoint, base station device), and multiple wireless reception devices(station, terminal device: station terminal device). A networkconfigured of the base station device and terminal devices is referredto as a basic service set (BSS: Basic service set, management range).The base station device and terminal devices are also collectivelyreferred to as wireless devices.

The base station device and terminal devices within the BSS each performcommunication based on CSMA/CA (Carrier sense multiple access withcollision avoidance). Although the present embodiment deals with aninfrastructure mode where a base station device communicates withmultiple terminal device, the method according to the present embodimentis also executable in an ad hoc mode where terminal devices directlycommunicate with each other. In ad hoc mode, a terminal device serves asthe base station device and forms a BSS. A BSS in ad hoc mode is alsoreferred to as an IBSS (Independent Basic Service Set). In thefollowing, a terminal device that forms an IBSS in ad hoc mode can bedeemed as being a base station device.

In an IEEE 802.11 system, each device is capable of transmittingmultiple types of transmission frames having a common frame format.Transmission frames are each defined by physical (Physical: PHY) layer,media access control (Medium access control: MAC) layer, and logicallink control (LLC: Logical Link Control) layer.

A PHY layer transmission frame is referred to as a physical protocoldata unit (PPDU: PHY protocol data unit, physical layer frame). A PPDUis configured of a physical layer header (PHY header) including headerinformation and the like for performing signal processing at thephysical layer, a physical service data unit (PSDU: PHY service dataunit, MAC layer frame) that is a data unit processed at the physicallayer, and so forth. A PSDU can be configured of an aggregated MPDU(A-MPDU: Aggregated MPDU) which is an aggregation of multiple MACprotocol data units (MPDU: MAC protocol data unit) that areretransmission increments in the wireless zone.

The PHY header includes reference signals such as short training field(STF: Short training field) used for detection, synchronization, and soforth of signals, long training field (LTF: Long training field) usedfor acquiring channel information for data demodulation, and so forth,and control signals such as signal (Signal: SIG) containing controlinformation for data demodulation, and so forth. STF is also classifiedinto legacy STF (L-STF: Legacy-STF), high throughput STF (HT-STF: Highthroughput-STF), very high throughput STF (VHT-STF: Very highthroughput-STF), or high efficiency STF (HE-STF: High efficiency-STF),or the like, in accordance with the corresponding standard, and in thesame way LTF and SIG are also classified into L-LTF, HT-LTF, VHT-LTF,HE-LTF, L-SIG, HT-SIG, VHT-SIG, and HE-SIG. VHT-SIG is furtherclassified into VHT-SIG-A and VHT-SIG-B.

Further, the PHY header can include information for identifying thetransmission source BSS of this transmission frame (hereinafter alsoreferred to as BSS identification information). Information identifyinga BSS may be an SSID (Service Set Identifier) of this BSS, for example,or a MAC address of the base station device of this BSS. Further,information identifying a BSS may be a value unique to the BSS (e.g.,BSS Color or the like), other than SSID or MAC address.

PPDUs are modulated in accordance with the corresponding standard. Forexample, PPDUs are modulated into orthogonal frequency divisionmultiplexing (OFDM: Orthogonal frequency division multiplexing) signalsin the IEEE 802.11n standard.

An MPDU is configured of a MAC layer header (MAC header) includingheader information for performing signal processing at the MAC layer andso forth, a MAC service data unit (MSDU: MAC service data unit) that isa data unit process at the MAC layer, or a frame body, and a frameinspection unit (Frame check sequence: FCS) for checking whether thereare no errors in the frame. Also, multiple MSDUs can be aggregated as anaggregated MSDU (A-MSDU: Aggregated MSDU).

Frame types of MAC layer transmission frames are generally classified into the three of management frames for managing inter-device connectionstate and so forth, control frames for managing inter-devicecommunication state, and data frames containing the actual communicationdata, each being further classified into multiple types of sub-frames.Control frames include reception complete notification (Ack:Acknowledge) frames, transmission request (RTS: Request to send) frames,reception preparation complete (CTS: Clear to send) frames, and soforth. Management frames include beacon (Beacon) frames, probe request(Probe request) frames, probe response (Probe response) frames,authentication (Authentication) frames, association request (Associationrequest) frames, association response (Association response) frames, andso forth. Data frames include data (Data) frames, polling (CF-poll)frames, and so forth. The devices can comprehend the frame type andsub-frame type received, by reading the content of the frame controlfield contained in the MAC header.

Note that Block Ack may be included in Ack. Block Ack can performreception complete notification regarding multiple MPDUs.

A beacon frame contains a cycle at which a beacon is transmitted (Beaconinterval) and a field (Field) to list an SSID. A base station device canperiodically notify a beacon frame within the BSS, and terminal devicescan comprehend the base station device in the periphery of the terminaldevices by receiving the beacon frame. Terminal devices comprehending abase station device based on a beacon frame notified by the base stationdevice is referred to as passive scanning (Passive scanning). On theother hand, a terminal device searching for a base station byannunciation of a probe request frame within the BSS is referred to asactive scanning (Active scanning). A base station device can transmit aprobe response frame as a response to the probe request frame, thecontent described on the probe response frame being equivalent to thatof a beacon frame.

After recognition of the base station device, the terminal deviceperforms connection processing as to the base station device. Connectionprocessing is classified into authentication (Authentication) proceduresand association (Association) procedures. The terminal device transmitsan authentication frame (authentication request) to the base stationdevice regarding which connection is desired. Upon receiving theauthentication frame, the base station device transmits anauthentication frame (authentication response) including a status code,indicating whether authentication of the terminal device is permissibleand so forth, to the terminal device. The terminal device can determinewhether or not it has been permitted authentication by the base stationdevice, by reading the status code described in authentication frame.Note that the base station device and the terminal device can exchangeauthentication frames multiple times.

Following authentication processing, the terminal device transmits anassociation request frame to the base station device to performassociation procedures. Upon receiving the association request frame,the base station device determines whether or not to permit associationof the terminal device, and transmits an association response frame tomake notification to that effect. In addition to a status codeindicating whether or not association processing is permissible, anassociation identification number (AID: Association identifier) ofidentifying the terminal device is described in the association responseframe. The base station device can manage multiple terminal devices bysetting different AIDs for each of the terminal devices to whichassociation permissions have been issued.

After the association processing has been performed, the base stationdevice and terminal device perform actual data transmission. Distributedcontrol mechanism (DCF; Distributed Coordination Function) andcentralized control mechanism (PCF: Point Coordination Function), andmechanisms where these have been extended (extended distributed channelaccess (EDCA: Enhanced districted channel access), hybrid controlmechanism (HCF: Hybrid coordination function), etc.), are described inthe IEEE 802.11 system. A case where a base station device transmitssignals to a terminal device by DCF will be exemplarily described below.

In DCF, the base station device and the terminal device perform carriersensing (CS: Carrier sense) in which the usage state of wirelesschannels in their periphery is confirmed, before communication. Forexample, in a case where the base station device that is thetransmitting station receives a signal that is higher than apredetermined clear channel assessment level (CCA level: Clear channelassessment level) on this wireless channel, transmission of atransmission frame over this wireless channel is delayed. Hereinafter, astate where a signal of CCA level or higher is detected will be referredto as a busy (Busy) state, and a state where a signal of CCA level orhigher is not detected as an idle (Idle) state of the wireless channel.CS performed based on power of signals each device has actually received(reception power level) in this way is referred to as physical carriersensing (physical CS). The CCA level is also referred to as carriersense level (CS level) or CCA threshold (CCA threshold: CCAT). In a caseof detecting signals at the CCA level or higher, the base station deviceand terminal device start operations of at least demodulating PHY layersignals.

The base station device performs carrier sensing for a frame interval(IFS: Inter frame space) corresponding to the type of transmission framebeing transmitted, and determines whether the wireless channel is in abusy state or idle state. The period over which the base station deviceperforms carrier sensing differs depending on the frame type andsub-frame type of the transmission frame that the base station device isgoing to transmit. Multiple IFSs having different periods are defined inthe IEEE 802.11 system, including a short frame interval (SIFS: ShortIFS) used for transmission frames to which the highest priority has beengiven, a poling frame interval (PCF IFS: PIFS) used for transmissionframes of which the priority is relatively high, a districted controlframe interval DCF IFS: DIFS) used for transmission frames of which thepriority is the lowest, and so forth. In a case of the base stationdevice transmitting a data frame by DCF, the base station device usesDIFS.

After standing by for a DIFS, the base station device further stands byfor a random back-off time, to prevent frame collision. A randomback-off time called contention window (CW: Contention window) is usedin the IEEE 802.11 system. CSMA/Ca assumes that a transmission frametransmitted from a certain transmitting station will be received by areceiving station in a state with no interference from anothertransmitting station. Accordingly, in a case where transmitting stationstransmit transmission frames at the same timing, the frames collide, andthe receiving station cannot receive correctly. Accordingly, each of thetransmitting stations standing by for a randomly-set amount of timebefore initiating transmission avoids frame collision. Upon determiningby carrier sensing that a wireless channel is in an idle state, the basestation device starts a CW countdown, and can acquire a transmissionright for the first time once the CW is 0, and transmit a transmissionframe to the terminal device. In a case where the base station devicedetermines by carrier sensing that the wireless channel is in a busystate during the CW countdown, the base station device stops the CWcountdown. In a case where the state of the wireless channel becomesidle, the base station device resumes the remaining CW countdownfollowing the preceding IFS.

The terminal device that is a receiving device receives the transmissionframe, reads the PHY header of the transmission frame, and demodulatesthe received transmission frame. The terminal device can recognizewhether or not the transmission frame is addressed to itself, by readingthe MAC header of the demodulated signals. Note that the terminal devicecan also recognize the addressee of the transmission frame based oninformation described in the PHY header (e.g., group identificationnumber (GID: Group identifier, Group ID) described in VHT-SIG-A).

In a case of determining that the received transmission frame has beenaddressed to itself, and successfully demodulating the transmissionframe without error, the terminal device must transmit an ACK frame,indicating that the frame was correctly received, to the base stationdevice that is the transmitting station. An ACK frame is one oftransmission frames with the highest priority, transmitted with only aSIFS period standby (no time taken for random back-off time). The seriesof communication ends with the base station device receiving the ACKframe transmitted from the terminal device. In a case where the terminaldevice is not able to receive the frame correctly, the terminal devicedoes not transmit an ACK. Accordingly, in a case where no ACK frame isreceived from the receiving station over a predetermined time (SIFS+ACKframe length) after having transmitted the frame, the base stationdevice deems the communication to have failed, and ends thecommunication. In this way, ending of one time of communication in theIEEE 802.11 system (also referred to as a burst) is always determined bywhether or not an ACK frame has been received, excluding cases oftransmission of an annunciation signal such as a beacon frame or thelike, or special cases such as cases of using fragmentation wheretransmission data is divided.

In a case of determining that the received transmission frame is notaddressed to itself, the terminal device sets a network allocationvector (NAV: Network allocation vector), based on the length (Length) ofthe transmission frame described in the PHY header or the like. Theterminal device does not attempt communication for the period set in theNAV. That is to say, during the period set to the NAV, the terminaldevice performs operations the same as a case of having determined byphysical CS that the wireless channel is in a busy state, andaccordingly communication control by the NAV is also referred to asvirtual carrier sensing (virtual CS). In addition to cases of being setbased on information described in the PHY header, the NAV is also set bya transmission request (RTS: Request to send) frame introduced toresolve a hidden node problem, and reception preparation complete (CTS:Clear to send) frames as well.

While each device performs carrier sensing and autonomously acquirestransmission right in DCF, a control station called a point coordinator(PC: Point coordinator) controls the transmission rights of the deviceswithin the BSS in PCF. Generally, the base station device serves as thePC, and the terminal devices within the BSS acquire transmission right.

A non-contention period (CFP: Contention free period) and a contentionperiod (CP: Contention period) are included in a communication period byPCF. The above-described communication based on DCF is performed duringthe CP, and it is during the CFP that the PC controls the transmissionright. The base station device serving as the PC performs annunciationwithin the BSS of a beacon frame in which is described the period of theCFP (CFP Max duration) and so forth, prior to communication by PCF. Notethat PIFS is used for transmission of the beacon frame annunciated atthe time of initiating PCF transmission, and transmission is performedwithout waiting for the CW. Terminal devices that receives the beaconframe set the CFP period described in the beacon frame to the NAV.Thereafter, the terminal devices can only acquire a transmission rightin a case of receiving a signal signaling transmission right acquisition(e.g., a data frame including a CF-poll) transmitted by the PC, untilthe NAV elapses, or a signal annunciating the end of the CFP within theBSS ((e.g., a data frame including a CF-end) is received. Packetcollisions do not occur within the same BSS during the CFP period, sothe terminal devices do not use the random back-off time used in DCF.

Hereinafter, the base station device and terminal devices are alsocollectively referred to as wireless devices. Also, informationexchanged at the time of a certain wireless device communicating withanother wireless device is also referred to as data (data).

The wireless devices support multiple access (MA: Multiple Access) inuplink (UL: Uplink). Uplink multiple access (UL-MU) includes uplinkspatial division multiple access (UL-SDMA: Uplink-Spatial DivisionMultiple Access, UL-MU-MIMO: Uplink Multi-User-Multiple Input MultipleOutput), uplink frequency division multiple access (UL-FDMA:Uplink-Frequency Division Multiple Access), and non-orthogonal multipleaccess (NOMA: Non-Orthogonal Multiple Access). Hereinafter, a wirelessdevice that initiates UL-MU transmission (transmits a frame notifying aUL-MU transmission initiation period, transmits a poll frame for UL-MUtransmission, first transmits a frame including control information forUL-MU transmission) is also referred to as an initiator (Initiator). Awireless device that transmits a responding frame (e.g., transmits aframe for participating in UL-MU transmission, transmits a framenotifying UL-MU transmission function information) as to the frame thatthe Initiator first transmits to initiate UL-MU transmission (alsoreferred to as a UL-MU poll frame) is also referred to as a responder(Responder). A wireless device that further transmits a responding frameas to a response frame transmitted by the Responder is also included inthe Responder. Note that the Initiator is also referred to as a firstterminal device, and the Responder is also referred to as a secondterminal device.

Hereinafter, a terminal device may be a terminal device other than abase station device (e.g., a Non-AP STA), or may be a terminal deviceincluding a base station device and terminal devices (e.g., a STA). Thatis to say, in the following description, a base station device canperform operations described as those of a terminal device. Also, theInitiator may be operations of the base station device and the Responderbe the terminal device in the present invention, or the Initiator may bethe terminal device and the Responder be the terminal device. Further,the Initiator may be operations of the terminal device and the Responderthe base station device in the present invention, or the Initiator maybe the base station device and the Responder be the base station device.

1. First Embodiment

FIG. 1 is a diagram illustrating an example of the configuration of awireless communication system according to the present embodiment. Abase station device 1-1 and terminal stations 2 a-1, 2 b-1, 2 c-1, and 2d-1 (hereinafter also collectively referred to as terminal devices 2-1)make up a management range 3-1. The wireless communication system mayalso be referred to as a BSS (Basic Service Set) or a management range.The base station device 1-1 and terminal devices 2-1 may also becollectively referred to as wireless devices 0-1.

Hereinafter, UL-MU-MIMO will be assumed as one example, but the presentembodiment is applicable to common UL-MU transmission. For example, thepresent embodiment is applicable to UL-OFDMA (Uplink-OrthogonalFrequency Division Multiple Access) as well.

FIG. 2 is a diagram illustrating an example of the device configurationof the base station device 1-1. The base station device 1-1 has aconfiguration including a higher-layer unit 10001-1, an autonomousdecentralized control unit 10002-1, a transmission unit 10003-1, areception unit 10004-1, and an antenna unit 10005-1.

The higher-layer unit 10001-1 is connected to another network, and cannotify the autonomous decentralized control unit 10002-1 of informationrelating to traffic. Information relating to traffic may be informationaddressed to a device, for example, or may be control informationincluded in a management frame or a control frame.

FIG. 3 is a diagram illustrating an example of the device configurationof the autonomous decentralized control unit 10002-1. The autonomousdecentralized control unit 10002-1 is a configuration including a CCAunit 10002 a-1, a back-off unit 10002 b-1, and a transmissiondetermination unit 10002 c-1.

The CCA unit 10002 a-1 can perform state determination of a wirelessresource (including determination of whether busy or idle), using one orboth of information relating to reception signal power of the wirelessresource and information relating to reception signals (includinginformation after decoding), notified from the reception unit 10004-1.The CCA unit 10002 a-1 can notify the back-off unit 10002 b-1 andtransmission determination unit 10002 c-1 of state determinationinformation regarding this wireless resource.

The back-off unit 10002 b-1 has a function of performing back-offprocessing using state determination information of the wirelessresource. The back-off unit 10002 b-1 can generate a CW, and further canperform countdown of the CW. For example, in a case where the statedetermination information of the wireless resource indicates idle,countdown of the CW can be performed, and in a case where the statedetermination information of the wireless resource indicates busy,countdown of the CW can be stopped. The back-off unit 10002 b-1 cannotify the transmission determination unit 10002 c-1 of the value of theCW.

Note that normal operations of the back-off unit 10002 b-1 in a casewhere no frame including an MU initiation frame (or MU Information) isreceived is also referred to as a first back-off (or first back-offunit), and operations of the back-off unit 10002 b-1 in a case where aframe including an MU initiation frame (or MU Information) is receivedis also referred to as a second back-off (or second back-off unit). MUinitiation frames and MU Information will be described later. Also,hereinafter, in a case where the back-off unit 10002 b-1 generates a CW,setting of a point in time at which transmission standby due to the CWends, is also referred to as the back-off unit instructing wirelessresource securing time. That is to say, operations of the back-off unit10002 b-1 can be restated as generating a CW and instructing wirelessresource securing time to the base station device 1-1.

Also, hereinafter, normal operations of the autonomous decentralizedcontrol unit 10002-1 in a case where no frame including an MU initiationframe (or MU Information) is received is also referred to as firstautonomous decentralized control (or first autonomous decentralizedcontrol unit, first wireless resource securing), and operations of theautonomous decentralized control unit 10002-1 in a case where a frameincluding an MU initiation frame (or MU Information) is received is alsoreferred to as second autonomous decentralized control (or secondautonomous decentralized control unit, second wireless resourcesecuring).

The transmission determination unit 10002 c-1 performs transmissiondetermination using one or both of the state determination informationof the wireless resource and the value of the CW. For example, if thestate determination information of the wireless resource indicates idleand the value of the CW is 0, the transmission unit 10003-1 can benotified of the transmission determination information. Alternatively,if the state determination information of the wireless resourceindicates idle, the transmission unit 10003-1 can be notified of thetransmission determination information.

The transmission unit 10003-1 is a configuration including a physicallayer frame generating unit 10003 a-1 and a wireless transmission unit10003 b-1. The physical layer frame generating unit 10003 a-1 has afunction of generating physical layer frames based on transmissiondetermination information notified from the transmission determinationunit 10002 c-1. The physical layer frame generating unit 10003 a-1subjects physical layer frames to error-correction encoding, modulation,prerecording filter multiplication, and so forth. The physical layerframe generating unit 10003 a-1 notifies the wireless transmission unit10003 b-1 of the generated physical layer frames.

The wireless transmission unit 10003 b-1 converts the physical layerframes generated by the physical layer frame generating unit 10003 a-1into radio frequency (RF: Radio Frequency) band signals, therebygenerating radio frequency signals. The processing performed by thewireless transmission unit 10003 b-1 includes digital-to-analogconversion, filtering, frequency conversion from baseband band to RFband, and so forth.

The reception unit 10004-1 is a configuration including a wirelessreception unit 10004 a-1 and a signal demodulation unit 10004 b-1. Thereception unit 10004-1 generates information relating to receptionsignal power from RF band signals that the antenna unit 10005-1receives. The reception unit 10004-1 can notify the CCA unit 10002 a-lof information relating to reception signal power and informationrelating to reception signals.

The wireless reception unit 10004 a-l has a function of converting theRF band signals received by the antenna unit 10005-1 into basebandsignals, and generating physical layer signals (e.g., physical layerframes). The processing performed by the wireless reception unit 10004a-1 includes frequency conversion processing from RF band to basebandband, filtering, and analog-to-digital conversion.

The signal demodulation unit 10004 b-1 has a function of demodulatingphysical layer signals generated by the wireless reception unit 10004a-1. The processing performed by the signal demodulation unit 10004 b-1includes channel equalization, de-mapping, error-correction decoding,and so forth. The signal demodulation unit 10004 b-1 can extractinformation included in the physical layer header, information includedin the MAC header, and information included in the transmission frame,for example from the physical layer signals. The signal demodulationunit 10004 b-1 can notify the higher-layer unit 10001-1 of the extractedinformation. Note that the signal demodulation unit 10004 b-1 canextract any or all of the information included in the physical layerheader, information included in the MAC header, and information includedin the transmission frame.

The antenna unit 10005-1 has a function of transmitting radio frequencysignals generated by the wireless transmission unit 10003 b-1 into thewireless space toward the wireless devices 0-1. The antenna unit 10005-1also has a function of receiving radio frequency signals transmittedfrom the wireless devices 0-1.

The device configuration of the terminal device 2-1 is the same as thatof the base station device 1-1, so description will be omitted.

FIG. 4 is a sequence chart illustrating an example of procedures forUL-MU transmission according to the first embodiment. Note that theexample illustrated in FIG. 4 is applicable to any MU upper limitnumber. An MU upper limit number is the upper limit value of the numberof terminal devices 2-1 that the base station device 1-1 can receive atthe same time in a case where multiple terminal devices 2-1 transmit atthe same time by UL-MU transmission. For example, in UL-MU-MIMO, the MUupper limit number preferably is equal to or less than the number ofantenna elements of the base station device 1-1. In UL-OFDMA, the MUupper limit number can be decided based on the number of divisions ofthe frequency band (Granularity: granularity). Note that in a case ofapplying non-orthogonal access (a method of multiplexing multipleterminal devices on the same wireless resource), this does not holdregarding the MU upper limit number, and the value may be greater thanthe number of antenna elements even in the case of UL-MU-MIMO. The MUupper limit number is also referred to as maximum number of multipleusers, maximum number of simultaneously transmitting terminals, numberof permissible multiple users, number of permissible multipletransmitting terminals, and so forth.

In the example illustrated in FIG. 4, terminal device 2 a-1 hasinitiated UL-MU transmission procedures. The terminal device 2 a-1transmits an MU initiation frame to the terminal device 2 b-1 andterminal device 2 c-1 (step S101). The MU initiation frame preferablyincludes a transmitting source address (the address of the terminaldevice 2 a-1 in the example illustrated in FIG. 4), and informationrelating to an UL-MU transmission start point-in-time, but does not needto include this. The base station device 1-1 and terminal device 2-1 cantransmit the MU initiation frame. The transmitter of the MU initiationframe is also referred to as the Initiator, and the receiver of the MUinitiation frame is also referred to as the Responder. Details of the MUinitiation frame configuration will be described later.

Next, the terminal device 2 b-1 and terminal device 2 c-1 that havereceived the MU initiation frame perform CW countdown (step S102). Theterminal device which has reached CW=0 within the UL-MU transmissioninitiation time as a result of the CW countdown (the terminal device 2b-1 in the example illustrated in FIG. 4) initiates UL-MU transmission(step S103).

On the other hand, a terminal device does not reach CW of 0 within theUL-MU transmission initiation time (the terminal device 2 c-1 in theexample illustrated in FIG. 4) does not participate in the UL-MUtransmission.

The terminal device 2-1 can initiate UL-MU transmission in a suitablemanner by the procedures of steps S101 through S103.

FIG. 5 is a diagram illustrating an example of the configuration of anMU initiation frame. The PHY layer frame has a configuration includingL-STF and L-LTF and L-SIG and a MAC Frame, the MAC Frame (MAC Frame)including a Frame Control field, a Duration field, an MU Informationfield, a TA (Transmitter Address) field, and a FCS field. The FrameControl field is a field including information relating to frame typeand so forth, and the Duration field is a field including informationrelating to NAVE settings (information relating to the length of atransmission burst containing a reception complete notification). ThatTA field is a field including information relating to the address of thetransmission source.

The MU Information field is a field including MU Information. MUInformation can include information used in the UL-MU transmissionaccording to the present embodiment. For example, MU Information cancontain any or all of information relating to the UL-MU transmissioninitiation time, information relating to a CW generation method, andinformation relating to a countdown method, information indicatinginformation identifying a group of the terminal devices 2-1 (sub-groupinformation), information relating to an LTF (or wireless resource)generation method, and information of an LTF (or wireless resource)transmission method.

Note that the configuration of an MU initiation frame is not restrictedto the example illustrated in FIG. 5, and that any configuration may beused as long as it is a frame that triggers UL-MU transmission. Further,a frame having a configuration equivalent to a control frame such as RTSor CTS can be used as an MU initiation frame, to protect terminaldevices that do not have functions to receive MU initiation frames(hereinafter also referred to as legacy terminal devices). Theconfiguration of an MU initiation frame may be the same as theconfiguration of a control frame such as RTS or CTS, with only part ofinformation in the fields being different, as in the example illustratedin FIG. 5, so as to have a frame configuration receivable by legacyterminal devices.

An MU initiation frame can include information relating to the upperlimit number of terminal devices participating in UL-MU transmission (MUupper limit number information), based on UL-MU transmission functioninformation of the management range 3-1. The base station device 1-1 cannotify the terminal devices 2-1 of function information regarding UL-MUtransmission of the BSS 3-1, such as information of whether or not theBSS 3-1 has UL-MU transmission functions, information of whether or notthe BSS 3-1 has functions of transmitting and receiving MU initiationframes, information relating to permission of UL-MU transmission,information indicating transmission permission of MU initiation frames,and information relating to the upper limit of the number ofparticipating terminal devices in UL-MU transmission. An MU initiationframe transmitted by the terminal devices 2-1 preferably includes MUupper limit number information that indicates a value equal to orsmaller than information relating to the upper limit of the number ofparticipating terminal devices in UL-MU transmission. Each of theterminal devices 2-1 can use multiple wireless resources. Now, if the MUupper limit number information is NMU, the number of wireless resourcesthat a terminal device 2-x uses in a certain UL-MU transmission is Nx,and a group of terminal devices 2-1 participating in the UL-MUtransmission is U, Nmu≥ΣxYNx is preferable.

The terminal devices 2-1 (or transmission determination unit 10002 c-1,autonomous decentralized control unit 10002-1) perform determination ofwhether transmittable, based on information relating to UL-MUtransmission initiation time. For example, even after having received anMU initiation frame, the terminal devices 2-1 can continue the CWcountdown, and initiate UL-MU transmission in a case where the CWreaches 0 within the UL-MU transmission initiation time. Alternatively,for example, determination of whether transmittable may be performedbased on the CW value at the point of receiving an MU initiation frame.For example, the terminal devices 2-1 can add information relating to aCW threshold value to an MU initiation frame. An arrangement may be madewhere a terminal device 2-1 acquires information relating to the CWthreshold value within the MU initiation frame, and UL-MU transmissionis initiated in a case where the CW value that this terminal device 2-1holds is a value equal to or lower than the CW threshold value, or UL-MUtransmission is initiated in a case of a value equal to or greater thanthe CW threshold value. Also, the terminal devices 2-1 can generate CWused in a dedicated manner for UL-MU transmission (hereinafter alsoreferred to as an MUCW), based on information relating to a CWgeneration method within an MU initiation frame. A back-off used in adedicated manner for UL-MU transmission is referred to as an MUback-off. Details of a method for MU back-off will be described later.

Note that information relating to the UL-MU transmission initiation timecan be set using an IFS (e.g., DIFS, SIFS, etc.). In formation relatingto the UL-MU transmission initiation time can also be set usinginformation relating to time sections (e.g., number of slots (slot)).

A terminal device 2-1 can attach information relating to wirelesssources used by this terminal device 2-1, information relating toreference signal generation method, and information relating toreference signal transmission method, to an MU initiation frame.

For example, a case will be assumed where a terminal device 2-1 that isthe Initiator transmits an MU initiation frame, and a wireless resourcethat this terminal device 2-1 uses is RA. Terminal devices 2-1 otherthan this terminal device 2-1 (or Responder will suffice) receive the MUinitiation frame, and use a wireless resource RB other than the wirelessresource RA used by the Initiator, whereby UL-MU transmission can besuitably carried out. For example, in the example illustrated in FIG. 4,information relating to a wireless resource used by terminal device 2a-1 can be attached to an MU initiation frame transmitted by theterminal device 2 a-1. The terminal device 2 b-1 can know the wirelessresource used by the terminal device 2 a-1, so suitable UL-MUtransmission can be performed by using a wireless resource other thanthe wireless resource used by the terminal device 2 a-1. For example, ina frequency division multiple access system such as OFDMA or the like, awireless resource may be information relating to a channel (e.g.,channel No. (index)).

Also, for example, a case will be assumed where a terminal device 2-1that is the Initiator transmits an MU initiation frame, and a referencesignal (e.g., LTF) generation method that this terminal device 2-1 usesis GA. Terminal devices other than this terminal device 2-1 (orResponder will suffice) receive the MU initiation frame, and use areference signal generation method GB other than the reference signalgeneration method GA used by the Initiator, whereby UL-MU transmissioncan be suitably carried out. For example, in the example illustrated inFIG. 4, information relating to a reference signal generation methodused by this terminal device 2 a-1 can be attached to an MU initiationframe transmitted by the terminal device 2 a-1. The terminal device 2b-1 can know the reference signal generation method used by the terminaldevice 2 a-1, so suitable UL-MU transmission can be performed by using areference signal generation method other than the reference signalgeneration method used by the terminal device 2 a-1. For example, inUL-MU-MIMO or DCMA (Code Division Multiple Access, code divisionmultiple access), a reference signal generation method may be ageneration method (e.g., scrambling, encoding, cyclic shift amount,etc.) for a reference signal (e.g., channel estimation reference signal,LTF, etc.).

Also, for example, a case will be assumed where a terminal device 2-1that is the Initiator transmits an MU initiation frame, and a referencesignal transmission method that this terminal device 2-1 uses is TA.Terminal devices 2-1 other than this terminal device 2-1 (or Responderwill suffice) receive the MU initiation frame, and use a referencesignal transmission method TB other than the reference signaltransmission method TA used by the Initiator. For example, in theexample illustrated in FIG. 4, information relating to a referencesignal transmission method used by terminal device 2 a-1 can be attachedto an MU initiation frame transmitted by the terminal device 2 a-1. Theterminal device 2 b-1 can know the reference signal transmission methodused by the terminal device 2 a-1, so suitable UL-MU transmission can beperformed by using a reference signal transmission method other than thereference signal transmission method used by the terminal device 2 a-1.For example, in UL-MU-MIMO or DCMA (Code Division Multiple Access, codedivision multiple access), a reference signal transmission method may bea transmission method (e.g., specification method of transmissionpoint-in-time, specification method of transmission band, specificationmethod of transmission carrier, specification method of transmissionpower, etc.) for a reference signal (e.g., channel estimation referencesignal, LTF, etc.).

The Base station device 1-1 can suitably perform propagation channelestimation regarding each terminal device 2-1 by using the above method.

For example, an MU initiation frame may include either or both of CWminincluding information relating to the maximum value of the CW and CWmaxincluding information relating to the minimum value of the CW. Theback-off unit 10002 b-1 can decide the range of the MUCW to be set basedon either or both of CWmin and CWmax, acquire a random value, and set tothe MUCW. The method of the back-off unit 10002 b-1 generating an MUCWis not restricted to this. The method of generating an MUCW preferablyis a method that avoids more terminal devices than the MU upper limitnumber from participating in the UL-MU transmission. The MUCW may be arandom value not based on another value, or may be a fixed value.

FIG. 6 is a sequence chart illustrating another example of proceduresfor UL-MU transmission according to the first embodiment. The exampleillustrated in FIG. 6 illustrates processing in a case wheretransmissions of MU participation frames have collided. The proceduresof processing illustrated in FIG. 6 is applicable to any MU upper limitnumber.

The terminal device 2 a-1 transmits an MU initiation frame (step S101e). The back-off units 10002 b-1 relating to the terminal device 2 b-1and the terminal device 2 c-1 execute CW countdown (Step S102 e). Theterminal devices 2-1 which have reached CW=0 (the terminal device 2 b-1and terminal device 2 c-1 in the example illustrated in FIG. 6) initiateUL-MU transmission (step S103 e).

The terminal device 2 b-1 and terminal device 2 c-1 can use differentwireless resources from the terminal device 2 a-1, based on the usagemethod of wireless resources by the terminal device 2 a-1 (e.g.,selection method of wireless resource to use, reference signalgeneration method, reference signal transmission method). However, theterminal device 2 b-1 and terminal device 2 c-1 do not know the wirelessresource usage method of each other, and accordingly there is apossibility that they will use the same wireless resource usage method.It is preferable in the present embodiment to have prepared morewireless resource usage methods than the MU upper limit number. In thiscase, the terminal device 2 b-1 and terminal device 2 c-1 can avoidselecting the same wireless resource (hereinafter also referred to ascollision, or Collision), by randomly selecting one from wirelessresource usage methods other than the wireless resource usage method ofthe terminal device 2 a-1. Note that the MU initiation frame can alsospecify the wireless resource usage method of the Responder.

Next, a method for suitably executing UL-MU transmission according tothe present embodiment will be described. In order for the base stationdevice 1-1 to perform AGC (Automatic Gain Control) and symbolsynchronization in UL-MU transmission, it is preferable that signalintensities arriving from the terminal devices 2-1 do not deviate. Also,in a case of UL-MU transmission being executed by spatial multiplexingof the terminal devices 2-1, signal intensities arriving from theterminal devices 2-1 preferably do not deviate, in order to maintain thecapabilities of the base station device 1-1 to divide the signalsarriving from the terminal devices 2-1.

For example, the terminal device 2-1 that is the Initiator can performtransmission power control for MU initiation frames, management frames,and control frames, as a method so that signal intensities arriving fromthe terminal devices 2-1 as observed by the base station device 1-1 donot deviate.

For example, the terminal device 2-1 that is the Initiator can performtransmission power control of MU initiation frames. For example, theterminal devices 2-1 that can participate in the UL-MU transmission canbe grouped (classified) by transmitting a MU initiation frame at a lowpower. Grouping is an act of extracting a part of terminal devices 2-1that satisfy predetermined conditions, using the information relating tothe environments, locations, properties, functions, and so forth, of theterminal devices 2-1. For example, transmitting an MU initiation frameat a low transmission power enables the terminal devices 2-1 that canreceive this MU initiation frame to be restricted. This is because therange of terminal devices 2-1 that can receive this MU initiation framehas been narrowed, by this MU initiation frame being transmitted bysmall power transmission.

For example, the terminal device 2-1 that is the Initiator can executetransmission power control when transmitting MU initiation frames. Thisterminal device 2-1 can transmit MU initiation frames with reducedtransmission power as to frames other than MU initiation frames, such asdata frames, management frames, control frames, and so forth.Transmission can also be performed of an MU initiation frame withreduced transmission power as to frames before executing transmission ofthe MU initiation frame (e.g., data frames, management frames, controlframes, and so forth, particularly Ack frames, RTS frames, CTS frames,beacon frames, etc.). Note that, for example, after a frame prior toexecuting transmission of an MU initiation frame has been transmitted,an MU initiation frame can be transmitted after standby of an IFS (e.g.,SIFS, PIFS, DIFS, EIFS, AIFS, etc.) period or another predeterminedperiod (period stipulated by the number of slots, etc.) Also, anarrangement may be made where no period is provided between a framebefore executing transmission of an MU initiation frame and transmissionof the MU initiation frame, and transmission may be made as anaggregated (Aggregation) frame. The distance between the terminaldevices 2-1 participating in the UL-MU transmission is reduced due tothe terminal device 2-1 that is the Initiator executing transmissionpower control, so the amount of deviation in signal intensities arrivingfrom the terminal devices 2-1 (or Initiator and Responder) participatingin the UL-MU transmission is reduced, and the base station device 1-1can perform suitable AGC and symbol synchronization.

FIG. 7 is a schematic diagram illustrating another example of thewireless communication system according to the present embodiment. Notethat the base station device 1-1 and the terminal devices 2-1 making upthe wireless communication system illustrated in FIG. 7 only differ fromthe base station device 1-1 and the terminal devices 2-1 making up thewireless communication system illustrated in FIG. 1 with regard tolocation information (or propagation channel information) thereof, andare of the same configuration, so description will be omitted. Note thatin the example illustrated in FIG. 7, the terminal device 2 a-1 isassumed to be the Initiator (hereinafter may also be referred to simplyas Initiator) and the transmitter of an MU initiation frame. Forexample, a range where signals transmitted by transmission power used toperform transmission of the MU initiation frame reach (although arrivalof signals is not restricted, this may be defined as, for example, areceiving wireless device being able to suitably demodulate or decodesignals, being able to detect a preamble, and so forth, or may bedefined as reception sensitivity of X dBm or above (the value of X isnot restricted, and X dBm or lower may be suitable)) will be referred toas range 23-1. A range where signals transmitted by transmission powerused to perform transmission of frames other than the MU initiationframe reach (e.g., frames transmitted in UL-MU transmission, RTS frames,CTS frames, etc.) will be referred to as range 23-2. Hereinafter,assumption will be made that the signal intensity of the terminaldevices 2-1 as observed by the base station device 1-1 is such thatdeviation is not occurring that would prevent the base station device1-1 from suitably performing AGC or symbol synchronization with regardto the terminal device 2 a-1 (in a case of using transmission powerdefining the range 23-2), terminal device 2 c-1, and terminal device 2d-1, and that the signal intensity of the terminal device 2 d-1 isdeviated from the signal intensity of the terminal device 2 a-1,terminal device 2 b-1, and terminal device 2 c-1, to where the basestation device 1-1 does not suitably perform AGC or symbolsynchronization.

In a case where the Initiator transmits an MU initiation frame attransmission power defining the range 23-2, the terminal device 2 b-1,terminal device 2 c-1, terminal device 2 d-1, and base station device1-1 can receive the MU initiation frame. That is to say, in the exampleillustrated in FIG. 7, the terminal device 2 b-1, terminal device 2 c-1,terminal device 2 d-1, and base station device 1-1 can be a Responder.For example, assumption will be made that the terminal device 2 b-1, andterminal device 2 c-1, and terminal device 2 d-1 are Responders, and thebase station device 1-1 performs reception of the UL-MU transmission. Inthis case, the Initiator and Responders execute the UL-MU transmission,so the base station device 1-1 cannot suitably perform AGC or symbolsynchronization.

Accordingly, the Initiator can perform transmission power control wherethe MU initiation frame is transmitted using transmission power definingthe range 23-1. By the Initiator performing transmission power control,the Responders are grouped into the terminal device 2 b-1 and terminaldevice 2 c-1. The terminal device 2 d-1 does not participate in theUL-MU transmission, so base station device 1-1 can suitably perform AGCand symbol synchronization.

Note that in the example illustrated in FIG. 7, the base station device1-1 cannot receive the MU initiation frame transmitted by the Initiator,and accordingly cannot be notified beforehand that the UL-MUtransmission frame will be transmitted. The base station device 1-1preferably is notified beforehand that the UL-MU transmission frame willbe transmitted. Hereinafter, a notification method of starting UL-MUtransmission to the base station device 1-1 by changing the MCS will bedescribed as one example.

The Initiator transmits a MU initiation frame using transmission powerdefining the range 23-2, for example, but just the MAC frame in the MUinitiation frame can have the MCS changed. Alternatively, just the MUInformation can have the MCS changed to perform encoding and modulation.For example, adding information notifying that UL-MU transmission willbe initiated to the PHY header within the MU initiation frame, andselecting a suitable MCS so that the PHY header information can bedecoded by the wireless devices 0-1 within the range 23-2, enables thebase station device 1-1 to be notified that UL-MU transmission will beinitiated after the MU initiation frame. Also, by encoding andmodulating the MU Information or MAC frame by an MCS that cannot bedecoded by the terminal device 2 d-1 but can be suitably decided by theterminal device 2 b-1 and terminal device 2 c-1, the MU initiation framereaches the terminal device 2 d-1 but the MU Information cannot bedecoded. Accordingly, the terminal device 2 d-1 does not participate inthe UL-MU transmission, so the base station device 1-1 can suitablyperform AGC and symbol synchronization.

Also, another example of executing UL-MU transmission more suitably byexecuting control frame transmission will be described. For example, theInitiator can transmit a control frame such as a transmission requestframe (RTS, etc.) or a reception preparation interference frame (CTS) orthe like immediately prior to transmitting an MU initiation frame. Aframe that the Initiator transmits immediately prior to the MUinitiation frame is also referred to as an MU transmission preparationframe. An MU transmission preparation frame can include information thatUL-MU transmission will be initiated, for example. The base stationdevice 1-1 can receive the MU initiation frame and acquire informationthat UL-MU transmission will be initiated, by the Initiator transmittingan MU transmission preparation frame using transmission power definingthe range 23-2, whereby the base station device 1-1 can be notified thatUL-MU transmission will be initiated.

Transmission of an MU transmission preparation frame can also be usedfor protection from legacy terminal devices. For example, an MUtransmission preparation frame may have a frame configuration that isdecodable by a legacy terminal device. In this case, a legacy terminaldevice situated within the range 23-2 can receive the MU transmissionpreparation frame. Accordingly, the Initiator can insert, into theDuration field, information relating to the UL-MU transmission(alternatively, Ack response that the base station device 1-1 transmitsafter UL-MU transmission) ending time (also referred to as Duration,length, wireless resource securing period, wireless resource reservationperiod, reservation period information, transmission period information,etc., for example). Note that the wireless resource securing period maybe inserted into the PHY header (e.g., length field), MAC header, ordata portion or the like.

Also, another example of executing UL-MU transmission more suitably bysetting CCA conditions will be described. For example, the base stationdevice 1-1 and the terminal devices 2-1 can hold information relating toconditions for participating in UL-MU transmission (MU participationpermissibility determination information). For example, MU participationpermissibility determination information may be a value restricting thereception signal intensity of the MU initiation frame. For example, acase will be assumed where the terminal device 2 d-1 may participate inthe UL-MU transmission in a case where the signal intensity of the MUinitiation frame (e.g., RSSI (Received Signal Strength Indicator), RCPI(Received Channel Power Indicator), etc.) is Y dBm or above (the valueof Y is not restricted, and Y dBm or lower may be suitable)), as the MUparticipation permissibility determination information. In a case wherean MU initiation frame transmitted by the Initiator is measured as beingY dBm or lower by the terminal device 2 d-1, the terminal device 2 d-1cannot participate in the UL-MU transmission. On the other hand, in acase where an MU initiation frame transmitted by the Initiator ismeasured as being Y dBm or higher by the terminal device 2 d-1, theterminal device 2 c-1 can participate in the UL-MU transmission, and canexecute suitable UL-MU transmission.

Also, the Initiator can include MU participation permissibilitydetermination information in the MU initiation frame and transmit, forexample. For example, the Initiator can change the content of the MUparticipation permissibility determination information for each UL-MUtransmission. Accordingly, the Initiator can change the content of theMU participation permissibility determination information in accordancewith the traffic information and channel information.

Also, the base station device 1-1 can transmit MU participationpermissibility determination information to the terminal devices 2-1.The base station device 1-1 can include MU participation permissibilitydetermination information in beacons, probe responses, authenticationresponses, association responses, etc., for example.

MU participation permissibility determination information is notrestricted to information relating to restriction of signal intensity.The MU participation permissibility determination information may beinformation relating to grouping in accordance with functions that theterminal devices 2-1 have or do not have, may be information grouped byindices of the terminal devices 2-1 (indicator, ID, index, AID, SID,TID, etc.), or may be a GID, for example.

FIG. 8 is a diagram illustrating an example of a GID configuration. AGID is a configuration where information relating to addressesindicating the terminal devices 2-1 has been stored in respectiveblocks. In the example illustrated in FIG. 8, a group of terminaldevices is allocated to each GID (Group ID). For example, GID1 indicatesinformation relating to STA2, STA3, STA4, and STA5. A GID indicatesinformation relating to the order of addresses of terminal devices.Alternatively, a GID has a configuration where the order of terminaldevices is understood. For example, GID1 and GID2 are made up of thesame terminal devices, but the order of the terminal deviceconfiguration is different. Hereinafter, the expression n'th terminaldevice will be used to distinguish the order in the GID configuration.For example, in GID31 the 1st terminal device is STA6, the 2nd terminaldevice is STA2, the 3rd terminal device is STA4, and the 4th terminaldevice is STA8.

For example, a terminal device 2-1 receiving an MU initiation frame canperform determination of participation permissibility to the UL-MUtransmission by the Initiator including a GID in the MU initiation frameas MU participation permissibility determination information. Forexample, settings may be made such that in a case where the MUparticipation permissibility determination information included in areceived MU initiation frame includes information indicating thisterminal device 2-1, participation in the UL-MU transmission ispermitted, or settings may be made such that participation in the UL-MUtransmission is permitted in a case where information indicating thisterminal device 2-1 is not included.

Next, a method for executing UL-MU transmission more suitably bytransmission power control will be described. This is a method whereeach terminal device 2-1 performs transmission power control in theUL-MU transmission, to avoid deviation in signal intensity of theterminal devices 2-1 as observed by the base station device 1-1.

For example, the Initiator may be transmitted including signal intensityrequest information in an MU initiation frame. The signal intensityrequest information is information indicating signal intensity observedby the base station device 1-1. For example, signal intensity requestinformation of Z dBm (Z is not restricted) means that in a UL-MUtransmission triggered by this MU initiation frame, the request forsignal intensity of each terminal device 2-1 is Z dBm.

For example, a terminal device 2-1 receive an MU initiation frameincluding signal intensity request information (signal intensity of ZdBm, as one example). The terminal device 2-1 performs transmissionpower control based on information relating to the propagation channel(e.g., propagation loss, path loss, long-span median value, short-spanmedian value, link margin, instantaneous propagation channel, etc.)between the base station device 1-1 and this terminal device 2-1. Forexample, assuming that the propagation loss between the base stationdevice 1-1 and the terminal device 2-1 is Z2−1 dB, the terminal device2-1 can calculate the transmission power P by P=−Z2−1−Z. The deviationof signal intensity of the terminal devices 2-1 as observed by the basestation device 1-1 can be reduced by transmission power control by theterminal devices 2-1, whereby suitable UL-MU transmission can beperformed.

Note that signal intensity request information is not restricted to theabove. Any arrangement may be used as long as information relating tothe propagation channel between the base station device 1-1 and theterminal devices 2-1.

The base station device 1-1 can also notify signal intensity requestinformation to the terminal devices 2-1. For example, the base stationdevice 1-1 can include signal intensity request information in beacons,probe responses, authentication responses, association responses, etc.,for example.

As described above, suitable UL-MU transmission can be realized byapplying the present embodiment to a wireless network. Improvement infrequency efficiency is realized while easily realizing a wirelessnetwork configuration.

2. Common to all Embodiments

A program running on the base station device 1-1 and terminal devices2-1 according to the present invention is a program that controls a CPUor the like (a program that causes a computer to function) so as torealize the functions of the above-described embodiments according tothe present invention. Information handled by these devices istemporarily stored in RAM at the time of processing, thereafter isstored in various types of ROM or HDDs, read out by the CPU asnecessary, and modification/wiring is performed. A recording mediumstoring the program may be any of semiconductor media (e.g., ROM,nonvolatile memory card, etc.), optical recording media (e.g., DVD, MO,MD, CD, BD, etc.), magnetic recording media (e.g., magnetic tape,flexible disk, etc.), and so forth. There also are cases where thefunctions of the above-described embodiments are realized not only bythe loaded program being executed, but also where the functions of thepresent invention are realized by processing being performedcollaboratively with an operating system, another application program,or the like, based on instruction of the program.

In a case of distributing to the market, the program may be stored in aportable recording medium and distributed, or may be transferred to aserver computer connected via a network such as the Internet. In thiscase, a storage device in the server computer is included in the presentinvention. Part or all of the above-described base station device 1-1and terminal devices 2-1 according to the above-described embodimentsmay typically be realized as an LSI that is an integrated circuit. Thefunction blocks of the base station device 1-1 and terminal devices 2-1may be formed as individual chips, or part or all may be formed as anintegrated chip. In a case where the function blocks are formed as anintegrated circuit, an integrated circuit control unit for controlthereof is added.

Techniques for forming an integrated circuit are not restricted to LSIs,and may be realized by dedicated circuits or general-purpose processors.In the event of the advent of an integrated circuit technology whichwould replace LSIs by advance of semiconductor technology, integratedcircuits according to such a technology may be used.

Note that the present invention is not restricted to the above-describedembodiments. The base station device 1-1 and terminal devices 2-1according to the present invention are not restricted to application tomobile station devices, and it is needless to say that this may beapplied to fixed or non-portable electronic equipment installed outdoorsor indoors, such as, for example, AV equipment, kitchen equipment,cleaning/laundry equipment, air conditioning equipment, officeequipment, vending equipment, other daily-use equipment, and so forth.

Although embodiments of the present invention have been described indetail with reference to the drawings, specific configurations are notrestricted to these embodiments, and designs and so forth that do notdepart for the essence of this invention are also included in the scopeof the Claims.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use in a terminal device,communication method, and communication system.

The present application claims priority based on Japanese PatentApplication No. 2015-090910 filed on Apr. 28, 2015, and the entirety ofJapanese Patent Application No. 2015-090910 is incorporated in thepresent international application.

REFERENCE SIGNS LIST

-   -   1-1 base station device    -   2-1, 2 a-1, 2 b-1, 2 c-1, 2 d-1 terminal device    -   3-1 management range    -   10001-1 higher-layer unit    -   10002-1 autonomous decentralized control unit    -   10002 a-1 CCA unit    -   10002 b-1 back-off unit    -   10002 c-1 transmission determination unit    -   10003-1 transmission unit    -   10003 a-1 physical layer frame generating unit    -   10003 b-1 wireless transmission unit    -   10004-1 reception unit    -   10004 a-1 wireless reception unit    -   10004 b-1 signal demodulation unit    -   10005-1 antenna unit    -   23-1, 23-2 range

The invention claimed is:
 1. A terminal device that performs uplinkmultiple access communication, the terminal device comprising: areception unit that receives a frame including uplink multiple accessconnection information; a first autonomous decentralized control unitthat instructs securing time of a wireless resource; and a secondautonomous decentralized control unit that instructs securing time ofthe wireless resource after reception of the frame including the uplinkmultiple access connection information, wherein the terminal device isinstructed securing time of the wireless resource by the firstautonomous decentralized control unit in a case that the frame includingthe uplink multiple access connection information is not received,wherein securing time of the wireless resource is instructed by thesecond autonomous decentralized control unit in a case that the frameincluding the uplink multiple access connection information is received,wherein the frame including the uplink multiple access connectioninformation further includes information associated with transmissionpower, wherein the second autonomous decentralized control unitreferences information instructing transmission permissibledetermination within the frame including the uplink multiple accessconnection information, and wherein the second autonomous decentralizedcontrol unit further determines participation in an uplink multipleaccess connection based on the information instructing the transmissionpermissible determination.
 2. The terminal device according to claim 1,wherein the second autonomous decentralized control unit generates acontention window that is different from a contention window that thefirst autonomous decentralized control unit generates.
 3. Acommunication method of a terminal device, the method comprising: a stepof receiving a frame including uplink multiple access connectioninformation; a step of performing first autonomous decentralized controlwhere securing time of a wireless resource is instructed; a step ofperforming second autonomous decentralized control where securing timeof the wireless resource is instructed after reception of a frameincluding the uplink multiple access connection information; a step ofinstructing securing time of the wireless resource by the firstautonomous decentralized control in a case that the frame including theuplink multiple access connection information is not received; and astep of instructing securing time of the wireless resource by the secondautonomous decentralized control in a case that the frame including theuplink multiple access connection information is received, wherein theframe including the uplink multiple access connection informationfurther includes information associated with transmission power, whereinthe step of performing the second autonomous decentralized controlcomprises referencing information instructing transmission permissibledetermination within the frame including the uplink multiple accessconnection information, and wherein the step of performing the secondautonomous decentralized control further comprises determiningparticipation in an uplink multiple access connection based on theinformation instructing the transmission permissible determination.